Give reasons for the following : Oxygen has less electron gain enthalpy with negative sign than sulphur.
The elements of group 16 have two electrons less than the nearest noble gas configuration. Therefore, they have a high tendency to accept two additional electrons and hence have large negative electron gain enthalpies next only to the halogens. The electron gain enthalpy of oxygen is however least negative in this group. This is due to its small size. As a result of which, the electron – electron repulsions in the relatively small 2p-subshell are comparatively large and hence the incoming electrons are not accepted with the same ease in case of other elements of this group.